The tenant/landlord relationship will always be a subject for debate. I was a tenant for a short time in Hong Kong, and had little to do with the landlord. My employment was terminated, and as a result, my employer had to settle any fees due with the landlord.
This brings the agreement into the forefront, as my employer was going to follow the agreement to the letter. It did not matter what I had said to my landlord, my employer would pay as agreed.
It is easy to forget what the tenant does, is often dictated by events beyond his control, I was not involved in the argument between my employer and the client over if the tunnel I was working on was dry or wet, and the change in costs as a result.
I shared my flat with a colleague, who had satellite TV installed, this did mean a change to our TV aerial outlet, that was about the only change to the flat. Not a clue to the charge to return to terrestrial TV. I was more worried about access to HSBC Hong Kong dollar account. Midland was at the time part of HSBC.
I say this as likely the tenant had other things on his mind to what he had altered in the flat. So in real terms, down to what the contract said. I know when my daughter had problems with her flat, I fixed them, without really more than a passing thought as to what was permitted. She had a problem, I fixed it, end of story. Minor works certificate never entered my mind.
If asked, I would have returned, taken readings, written out a minor works certificate, and also a bill for the work. In this case, the wire was not to any permitted work, but as to claiming against the tenant, one has to prove the tenant did not end up forced to take the action. You could take them to court, but is it really worth the effort?